The present invention relates to certain optimally sized and shaped media for use in electroplating composite articles and in particular for electroplating relatively small sized electronic components.
In order to plate composite articles that have both conductive and non-conductive portions, it is generally necessary to add a conductive material to the articles being plated. This conductive material is referred to as media or filler and is typically comprised of metal spheres that are of similar dimensions to the parts to be plated. This media serves the dual function of imparting electrical conductivity to the load and of improving the movement of the parts during the plating process. It is normal practice to use volume ratio of media to articles of at least 1.5/1, with ratios as high as 4/1 or 5/1 not being uncommon. Without the use of media it would be nearly impossible to obtain satisfactory deposition on composite articles using conventional barrel plating equipment. Recently, specialized equipment has been developed with large current feeder areas (U.S. Pat. Nos. 6,193,858, 5,487,824, 5,565,079) which can plate some types of composite articles without media, however, even this equipment requires the use of media in certain situations, such as to plate composite articles that have small conductive areas.
The use of media, although generally necessary, has several drawbacks. Plating times are greatly extended due to the increased surface area attributable to the media. The preponderance of metal is deposited on the media and not on the articles to be plated. Additionally, it is often difficult to separate the media from the plated articles. Moreover, the load size of the articles to be plated in a given plating apparatus is reduced since media consumes a great deal of volume in the plating chamber. Therefore, it is desirable to reduce the volume of media used during plating and to select media that is easily separable from the plated articles. The present invention now resolves these problems and accomplishes the desired goals.